1. Field of the Invention
The present invention relates to a battery in which the open circuit voltage in full charge state is about 3 V.
2. Description of the Related Art
In recent years, high performance, miniaturization, and portability of electronic devices have been developed as electronic engineering and the like have been advanced. For secondary batteries used as a power source for these electronic devices, high performance and miniaturization have been strongly demanded. As such a secondary battery, for example, lithium ion secondary batteries have been developed and in practical use.
Specially, as a backup power source, the coin-type (button-type) lithium ion secondary battery with a battery voltage of about 3 V using an oxide containing lithium (Li) and manganese (Mn) such as Li4Mn5O12 for the cathode active material has been widely utilized (for example, refer to Japanese Unexamined Patent Application Publication No. 2004-95399). Such a lithium ion secondary battery provides a high energy density and is lightweight. Therefore, it is considered that such a secondary battery is not only used as a backup power source but also used as a power source for electrical calculators, digital still cameras, portable radios or the like.